Taig lathe tailstock tramming animations. Zero front/back
readings.It is the tailstock that is moved horizontally (typically opposing
set screws) and/or
vertically (shims or grinding) into proper position as indicated by the dial
test gage.

Zero top/bottom readings.

CAUTION: DO NOT TURN THE LATHE ON

Another method
used to center the tailstock
with respect to the tailstock
is to
mount a dial test gage
in thespindle & a dowel pin in the tailstock-mounted drill
chuck; another method uses the dead center.
The test dial indicator
is mounted
in a collet. Rotate the spindle front & back while
adjusting the
tailstock offset, making half-the-difference changes between them until
there are no differences.